(SELECT feed_url, site_url, title, subscribers FROM ttrss_feedbrowser_cache UNION ALL
SELECT feed_url, site_url, title, subscribers FROM ttrss_linked_feeds) AS qqq
WHERE
(SELECT feed_url, site_url, title, subscribers FROM ttrss_feedbrowser_cache UNION ALL
SELECT feed_url, site_url, title, subscribers FROM ttrss_linked_feeds) AS qqq
WHERE